Self-sealing septum assembly

ABSTRACT

Exemplary septum assemblies include first and second housing components each defined by at least an inner surface, at least one sealing strip disposed at least partially on at least one of the inner surfaces of the housing components, and a compression member at least partially surrounding the housing components.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/040,358, filed Mar. 28, 2008, the entirecontents of which is incorporated by reference.

BACKGROUND

Implantable stimulators are often used to treat a variety of medicaldisorders by providing electrical stimulation pulses via one or moreelectrodes placed at a desired stimulation site within a patient. Theelectrodes are typically disposed on one or more leads that are coupledto the implantable stimulator.

One type of implantable stimulator includes an implantable pulsegenerator (IPG) configured to provide spinal cord stimulation to apatient. At least one stimulating lead with one or more electrodesdisposed thereon may be coupled to the IPG. In this manner, the lead maybe implanted epidurally near the patient's spine and the IPG may beimplanted in a surgically convenient location (e.g., within asubcutaneous pocket created within the torso of the patient). The IPGmay then generate and deliver electrical stimulation pulses via the oneor more electrodes to the spine in accordance with stimulationparameters configured to treat a particular medical disorder.

To facilitate coupling of a lead to an implantable stimulator, thestimulator may include a header assembly having a receptacle configuredto receive a proximal portion of the lead. After the lead has beeninserted into the receptacle, a set screw may be tightened against thelead to secure the lead in place.

However, it is often difficult to prevent body fluid and tissue ingressonto or around the set screw. These fluids and/or tissues may causecorrosion and/or premature failure of one or more components within thestimulator. They may also possibly prevent the set screw from beingreleased in future procedures. In systems where the set screw is anactive electrical element, fluid ingress may create accessory electricalcurrent pathways that could reduce the effectiveness of the therapyprovided by the stimulator or cause harm to the patient.

SUMMARY

Exemplary septum assemblies include first and second housing componentseach defined by at least an inner surface, at least one sealing stripdisposed at least partially on at least one of the inner surfaces of thehousing components, and a compression member at least partiallysurrounding the housing components.

Exemplary stimulators include a housing configured to house electroniccircuitry configured to generate electrical stimulation, a receptacle atleast partially disposed within the housing configured to receive aproximal portion of a lead, an orifice within the housing and having anopening in communication with an outer surface of the housing, theorifice being configured to receive a set screw, and a septum assemblycoupled to the housing and configured to cover the opening of theorifice. The septum assembly includes first and second housingcomponents each defined by at least an inner surface, at least onesealing strip disposed at least partially on at least one of the innersurfaces of the housing components, and a compression member at leastpartially surrounding the housing components. The at least one sealingstrip is configured to create a seal over the opening of the orifice.

Exemplary systems include a stimulator having an orifice within ahousing thereof and a septum assembly coupled to the stimulator andconfigured to cover an opening of the orifice. The septum assemblyincludes first and second housing components each defined by at least aninner surface, a first sealing strip disposed at least partially on theinner surface of the first housing component, a second sealing stripdisposed at least partially on the inner surface of the second housingcomponent, and a compression member at least partially surrounding thehousing components. The first and second sealing strips are configuredto create a seal over the opening of the orifice.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various embodiments of theprinciples described herein and are a part of the specification. Theillustrated embodiments are merely examples and do not limit the scopeof the disclosure.

FIG. 1 illustrates an exemplary stimulator that may be used to applyelectrical stimulation to one or more stimulation sites within a patientaccording to principles described herein.

FIG. 2 is a perspective view of a stimulator and a header assemblyaccording to principles described herein.

FIG. 3A is a perspective view of an exemplary self-sealing septumassembly in a closed state according to principles described herein.

FIG. 3B is a perspective view of the exemplary self-sealing septumassembly of FIG. 3A in an open state according to principles describedherein.

FIG. 4A is a cross sectional side view of a header assembly with aseptum assembly disposed therein according to principles describedherein.

FIG. 4B is another cross sectional side view of the header assembly ofFIG. 4A according to principles described herein.

Throughout the drawings, identical reference numbers designate similar,but not necessarily identical, elements.

DETAILED DESCRIPTION

Systems, apparatuses, and methods for providing a reliable connectionbetween an implantable stimulator and a lead coupled thereto aredescribed herein. In some examples, a stimulator may be coupled to aheader assembly, lead extension assembly, or other device having areceptacle disposed therein that is configured to receive a proximalportion of a lead. A hole configured to receive a set screw may also bedisposed within the header assembly, lead extension assembly, or otherdevice such that the set screw may be tightened with a wrench againstthe proximal portion of the lead.

In some examples, a self-sealing septum assembly may be configured tocreate a seal over an opening of the hole. The septum assembly mayinclude first and second housing components each defined by at least aninner surface, a first sealing strip disposed at least partially on theinner surface of the first housing component, a second sealing stripdisposed at least partially on the inner surface of the second housingcomponent, and a compression member at least partially surrounding thehousing components.

Upon insertion of a wrench in between the housing components, the wrenchexerts a lateral force against the housing components. This lateralforce causes the compression member to expand and the housing componentsto move away from one another. In this manner, the wrench may passthrough the septum assembly and into the hole to tighten or loosen theset screw.

As will be described in more detail below, the septum assembly isconfigured to minimize damage to the sealing strips located in the innersurfaces of the housing components. Moreover, the septum assemblydescribed herein is configured to prevent fluid and/or tissue ingressinto the set screw hole such that a more reliable and secure connectionmay be made between the set screw and the lead.

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present systems and apparatuses. It will beapparent, however, to one skilled in the art that the present systemsand apparatuses may be practiced without these specific details.Reference in the specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least oneembodiment. The appearance of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment.

To facilitate an understanding of the systems and methods describedherein, a more detailed description of an implantable stimulator and itsoperation will now be given. FIG. 1 illustrates an exemplary stimulator100 that may be used to apply electrical stimulation to one or morestimulation sites within a patient. The stimulation site may include anynerve or other tissue within the patient such as, but not limited to, anerve within the spinal cord region, the heart, or any other location asmay serve a particular application.

In some examples, the exemplary stimulator 100 shown in FIG. 1 mayinclude at least one lead 101 coupled thereto. To this end, thestimulator 100 may include a header assembly 111 configured tofacilitate coupling of the lead 101 to the stimulator 100. The headerassembly 111 will be described in more detail below. Additionally oralternatively, the lead 101 may be coupled to the stimulator 100 via alead extension.

In some examples, the at least one lead 101 includes a number ofelectrodes 102 through which electrical stimulation current may beapplied to the stimulation site. It will be recognized that the at leastone lead 101 may include any number of electrodes 102 arranged in anyconfiguration as best serves a particular application. It will berecognized that the stimulator 100 may additionally or alternatively becoupled to one or more catheters through which one or more therapeuticdrugs may be applied to the stimulation site.

As illustrated in FIG. 1, the stimulator 100 includes a number ofcomponents. For example, the stimulator 100 may include a power source103, coil 104, electrical circuitry 105, and/or a programmable memoryunit 106. It will be recognized that the stimulator 100 may includeadditional and/or alternative components as best serves a particularapplication.

The power source 103 is configured to output voltage used to supply thevarious components within the stimulator 100 with power and/or togenerate the power used for electrical stimulation. The power source 103may include a primary battery, a rechargeable battery (e.g., alithium-ion battery), a super capacitor, a nuclear battery, a mechanicalresonator, an infrared collector (receiving, e.g., infrared energythrough the skin), a thermally-powered energy source (where, e.g.,memory-shaped alloys exposed to a minimal temperature differencegenerate power), a flexural powered energy source (where a flexiblesection subject to flexural forces is part of the stimulator), abioenergy power source (where a chemical reaction provides an energysource), a fuel cell, a bioelectrical cell (where two or more electrodesuse tissue-generated potentials and currents to capture energy andconvert it to useable power), or the like.

The coil 104 is configured to receive and/or emit a magnetic field (alsoreferred to as a radio frequency (RF) field) that is used to communicatewith, or receive power from, one or more external devices. Suchcommunication and/or power transfer may include, but is not limited to,transcutaneously receiving data from the external device, transmittingdata to the external device, and/or receiving power used to recharge thepower source 103.

For example, an external battery charging system (EBCS) 107 may beprovided to generate power that is used to recharge the power source 103via any suitable communication link. Additional external devicesincluding, but not limited to, a hand held programmer (HHP) 108, aclinician programming system (CPS) 109, and/or a manufacturing anddiagnostic system (MDS) 110 may also be provided and configured toactivate, deactivate, program, and/or test the stimulator 100 via one ormore communication links. It will be recognized that the communicationlinks shown in FIG. 1 may each include any type of link used to transmitdata or energy, such as, but not limited to, an RF link, an infrared(IR) link, an optical link, a thermal link, or any other energy-couplinglink.

Additionally, if multiple external devices are used in the treatment ofa patient, there may be communication among those external devices, aswell as with the implanted stimulator 100. It will be recognized thatany suitable communication link may be used among the various devicesillustrated.

The external devices shown in FIG. 1 are merely illustrative of the manydifferent external devices that may be used in connection with thestimulator 100. Furthermore, it will be recognized that the functionsperformed by any two or more of the external devices shown in FIG. 1 maybe performed by a single external device.

The stimulator 100 may also include electrical circuitry 105 configuredto generate the electrical stimulation current that is delivered to thedamaged neural tissue via one or more of the electrodes 102. Forexample, the electrical circuitry 105 may include one or moreprocessors, capacitors, integrated circuits, resistors, coils, and/orany other component configured to generate electrical stimulationcurrent.

The stimulator 100 may also include a programmable memory unit 106configured to store one or more stimulation parameters. The programmablememory unit 106 allows a patient, clinician, or other user of thestimulator 100 to adjust the stimulation parameters such that thestimulation applied by the stimulator 100 is safe and effective intreating a particular patient. The programmable memory unit 106 mayinclude any type of memory unit such as, but not limited to, randomaccess memory (RAM), static RAM (SRAM), a hard drive, or the like.

The stimulator 100 of FIG. 1 is illustrative of many types ofstimulators that may be used in accordance with the systems and methodsdescribed herein. For example, the stimulator 100 may include animplantable pulse generator (IPG), a microstimulator, a pacemaker, adefibrillator, an external trial stimulator, and/or any other type ofdevice configured to deliver electrical stimulation to a stimulationsite within a patient.

FIG. 2 is a perspective view of the stimulator 100 of FIG. 1 andillustrates the header assembly 111 in more detail. In some examples,the header assembly 111 is configured to facilitate coupling of the lead101 to the stimulator 100. While a header assembly 111 is shown in FIG.2, the lead 101 may alternatively be coupled directly to the stimulator100 or coupled to the stimulator 100 using a lead extension assembly.

As shown in FIG. 2, the stimulator 100 may include a main housing 120configured to house one or more components of the stimulator 100. Forexample, the housing 120 may be configured to house the power source103, coil 104, electrical circuitry 105, and/or programmable memory unit106. To this end, the housing 120 may include, but is not limited to, ahermetic encasing configured to prevent entry therein of bodily fluids.The housing 120 may be made out of any suitable material including, butnot limited to, metal, metal alloys, ceramics, plastics, polymers,and/or combinations thereof.

The header assembly 111 may be hermetically coupled to the main housing120, as shown in FIG. 2. The header assembly 111 may be made out of anysuitable material as may serve a particular application. For example,the header assembly 111 may be made out of metal, metal alloys,ceramics, plastics, polymers, and/or combinations thereof.

To facilitate electrical coupling of a lead 101 to the electricalcircuitry 105 housed within the housing 120, the header assembly 111 mayinclude a receptacle 121 dimensioned to receive a proximal portion ofthe lead 101. An electrical conductor 125 (e.g., one or more conductivewires) may be coupled to the receptacle 121 at one end and to afeedthrough assembly 126. The feedthrough assembly 126 is electricallycoupled to the electrical circuitry 105 within the housing 120.

The surface defining the receptacle 121 may include at least oneconductive portion configured to maintain electrical contact with theproximal portion of the lead 101 when the lead 101 is inserted withinthe receptacle 121. To this end, the proximal portion of the lead 101may include a conductive connector pin and/or one or more conductivecontacts disposed thereon configured to be in physical contact with theconductive portion of the receptacle 121.

In some examples, the header assembly 111 may include a threaded hole ororifice 123 extending substantially perpendicular from the receptacle121 to the outer surface of the header assembly 111. It will berecognized that the hole 123 may alternatively extend from thereceptacle 121 at any suitable angle. The threaded hole 123 isconfigured to receive a set screw 124. The set screw 124 may be screweddown within the threaded hole 123 until contact is made with theproximal portion of the lead 101. In this manner, a secure mechanicalconnection may be maintained between the header assembly 111 and thelead 101. In some examples, an electrical connection may additionally bemade between the set screw 124 and the lead 101 when the set screw 124is in contact with the proximal portion of the lead 101. To remove thelead 101 from the header assembly 111, the set screw 124 may beloosened.

As mentioned, it is often difficult to prevent body fluid and tissueingress onto or around the connection made between the set screw 124 andthe inserted lead 101. These fluids and/or tissues may cause corrosionand/or premature failure of one or more components within the stimulator100. In systems where the set screw 124 is an active electrical element,fluid ingress may create accessory electrical current pathways thatcould reduce the effectiveness of the therapy provided by the stimulator100 or cause harm to the patient.

To this end, the header assembly 111 may include a self-sealing septumassembly 130 (or simply “septum assembly 130”) configured to preventfluid and tissue ingress into or around the connection made between theset screw 124 and the inserted lead 101. As will be described in moredetail below, the septum assembly 130 may be configured to create a sealover the opening of hole 123 to prevent fluid and tissue ingress intothe hole 123. At the same time, the septum assembly 130 is configured toallow passage therethrough of a wrench to tighten or loosen the setscrew 124 disposed within the hole 123.

FIG. 3A is a perspective view of an exemplary septum assembly 130 in aclosed state that may be used in accordance with the systems and methodsdescribed herein. FIG. 3B shows the septum assembly 130 of FIG. 3A in anopen state. As shown in FIGS. 3A-3B, the septum assembly 130 may includefirst and second housing components 131-1 and 131-2 (collectivelyreferred to as housing components 131), first and second sealing strips132-1 and 132-2 (collectively referred to as sealing strips 132)disposed on an inner surface of the housing components 131, and acompression member 133 surrounding the housing components 131. Each ofthese components will be described in more detail below.

As shown in FIG. 3A, the septum assembly 130 may be cylindrically shapedwith each housing component 131 in the form of a half cylinder. Hence,each housing component 131 may be defined by a planar inner surface 134and a curved outer surface 135. It will be recognized that the housingcomponents 131 may be of any suitable shape and size as may serve aparticular application. For example, each of the housing components 131may be generally rectangular.

In some examples, the housing components 131 may each be made of agenerally rigid material. Such materials may include, but are notlimited to, plastic, metal, metal alloys, and the like. As will bedescribed in more detail below, the rigidity of the housing components131 may serve to protect the sealing strips 133 from exposure and/ordamage caused by a wrench being inserted into the septum assembly 130.

To aid in the alignment of a wrench with the set screw 124, each of thehousing components 131 may include a tapered portion 136 configured toguide the wrench into the hole 123 of the header assembly 111. Insertionof the wrench into the hole 123 will be described in more detail below.

As shown in FIGS. 3A-3B, a sealing strip 132 may be coupled to an innersurface 134 of one or more of the housing components 131. In someexamples, each sealing strip 132 is configured to extend along theentire length of the inner surface 134 of its corresponding housingcomponent 131 and wrap at least partially around the curved outersurface 135 of the corresponding housing component 131. Alternatively,each sealing strip 132 may only partially extend along the inner surface134 of its corresponding housing component 131. It will be recognizedthat two sealing strips 132 are shown in FIGS. 3A-3B for illustrativepurposes and that one sealing strip 132 or more than two sealing strips132 may alternatively be included as may serve a particular application.

In some examples, the sealing strips 132 are configured to create a sealover the hole 123 of the header assembly 111 when pressed against eachother. To this end, the sealing strips 132 may be made out of anysuitable material configured to create a seal when pressed against eachother. For example, the sealing strips 132 may be made out of siliconeor any other suitable material.

As shown in FIGS. 3A-3B, the compression member 133 is configured tosurround the housing components 131. In its natural state (i.e., in theclosed state shown in FIG. 3A), the compression member 133 is configuredto exert a compressive force on the housing components 131 such that thesealing strips 132 are pressed against each other to create a seal. Aswill be described in more detail below, insertion of a wrench into theseptum assembly 130 causes the compression member 133 to expand (i.e.,to the open state shown in FIG. 3B), thereby allowing the housingcomponents 131 to move away from each other and create a passage way forthe wrench into the hole 123. When the wrench is removed from the septumassembly 130, the compression member 133 resumes its compressed state inorder to maintain the seal.

Hence, the compression member 133 may made out of any elastic materialsuch as, but not limited to, silicon, rubber, and/or combinations orderivatives thereof. Additionally, the composition of the compressionmember 133 may be such that it may be stretched sufficiently to allowfull insertion of a wrench in between the housing components 131 of theseptum assembly 130 as well as resilient enough to provide a sufficientreturning force to press the sealing strips 131 against each other tocreate a seal over the hole 123 of the header assembly 111 when thewrench is removed.

The compression member 133 may vary in thickness as may suit aparticular application. For example, the compression member 133 mayinclude a relatively thin compression band, as shown in FIGS. 3A-3B. Insome alternative embodiments, the compression member 133 may include arelatively thick body of silicone in which the housing components 131are disposed. In these embodiments, the compression member 133 mayfacilitate separation of the housing components 131 through thedisplacement of various portions of the body of silicone from one regionto another. The silicone body may be an integrally molded part of thestimulator 100, for example.

An illustrative application of the septum assembly 130 will be describedin connection with FIGS. 4A-4B. FIG. 4A is a cross sectional side viewof the header assembly 111 with the septum assembly 130 includedtherein. As shown in FIG. 4A, a central axis of the septum assembly(represented in FIGS. 4A-4B by dashed line 140) is aligned with acentral axis of the hole 123. The sealing strips 132 may extend in adirection generally perpendicular to the central axis 140.

When a wrench 141 is inserted into the septum assembly 130 along thecentral axis 140, the wrench 141 exerts a lateral force against thehousing components 131. This lateral force causes the housing components131 to move away from one another so that the wrench may pass throughthe septum assembly 130 and into the hole 123.

FIG. 4B shows the header assembly 111 and septum assembly 130 of FIG. 4Aafter the wrench 141 has passed in between the housing components 131and into the hole 123. As shown in FIG. 4B, the wrench is engaged withthe set screw 124. A user may then tighten or loosen the set screw asdesired with the wrench 141.

For example, a user may tighten the set screw 124 to secure the proximalportion of a lead 101 within the receptacle 121. To remove the lead 101from the receptacle 121, the user may loosen the set screw 124. In someexamples, the bottom surface of the housing components 131 may beconfigured to serve as a stop that prevents over loosening of the setscrew 124. In this manner, removal of the set screw 124 from the hole123 may be prevented.

It will be recognized that the wrench 141 shown in FIGS. 4A-4B mayinclude any device as may serve a particular application. For example,the wrench 141 may include an Allen wrench, a screw driver, a star key,a square key, a hexagonal key, and/or variations thereof.

Upon removal of the wrench from the hole 123 and septum assembly 130,the compression force exerted by the compression member 133 pushes thehousing components 131 together until the sealing strips 132 reform aseal over the hole 123.

The preceding description has been presented only to illustrate anddescribe embodiments of the invention. It is not intended to beexhaustive or to limit the invention to any precise form disclosed. Manymodifications and variations are possible in light of the aboveteaching.

1. A septum assembly comprising: first and second housing componentseach defined by at least an inner surface; at least one sealing stripdisposed at least partially on at least one of said inner surfaces ofsaid housing components; and a compression member at least partiallysurrounding said housing components.
 2. The septum assembly of claim 1,wherein: said compression member is configured to exert a force on saidfirst and second housing components such that said at least one sealingstrip creates a seal between said inner surfaces of said housingcomponents.
 3. The septum assembly of claim 1, wherein said compressionmember is configured to expand to allow said first and second housingcomponents to separate one from another to facilitate passagetherebetween of a wrench.
 4. The septum assembly of claim 1, whereinsaid housing components are made of a generally rigid material.
 5. Theseptum assembly of claim 1, wherein said at least one sealing strip ismade of a silicone material.
 6. The septum assembly of claim 1, whereinsaid compression member is made of an elastic material.
 7. The septumassembly of claim 1, wherein each of said housing components is furtherdefined by a curved outer surface, and wherein said at least one sealingstrip extends at least partially along one or more of said curved outersurfaces.
 8. The septum assembly of claim 1, wherein at least one ofsaid housing components comprises a tapered portion configured to guidea wrench in between said first and second housing components.
 9. Theseptum assembly of claim 1, wherein said at least one sealing stripcomprises: a first sealing strip disposed at least partially on saidinner surface of said first housing component; and a second sealingstrip disposed at least partially on said inner surface of said secondhousing component.
 10. The septum assembly of claim 1, wherein saidcompression member comprises at least one of a compression band and asilicone body integrally molded into a stimulator.
 11. The septumassembly of claim 1, wherein said first and second housing componentsare configured to serve as a stop to prevent over loosening of a setscrew.
 12. A stimulator comprising: a housing configured to houseelectronic circuitry configured to generate electrical stimulation; areceptacle at least partially disposed within said housing configured toreceive a proximal portion of a lead; an orifice within said housing andhaving an opening in communication with an outer surface of saidhousing, said orifice being configured to receive a set screw, said setscrew configured to be tightened against said proximal portion of saidlead; and a septum assembly coupled to said housing and configured tocover said opening of said orifice; wherein said septum assemblycomprises first and second housing components each defined by at leastan inner surface, at least one sealing strip disposed at least partiallyon at least one of said inner surfaces of said housing components, and acompression member at least partially surrounding said housingcomponents; wherein said at least one sealing strip is configured tocreate a seal over said opening of said orifice.
 13. The stimulator ofclaim 12, wherein said compression member is configured to exert a forceon said first and second housing components such that said at least onesealing strip creates said seal.
 14. The stimulator of claim 12, whereinsaid compression member is configured to expand to allow said first andsecond housing components to separate one from another to facilitatepassage therebetween of a wrench into said orifice.
 15. The stimulatorof claim 12, wherein said housing components are configured to preventover loosening of said set screw within said orifice.
 16. The stimulatorof claim 12, wherein said at least one sealing strip is made of asilicone material.
 17. The stimulator of claim 12, wherein saidcompression member is made of an elastic material.
 18. The stimulator ofclaim 12, wherein said compression member comprises at least one of acompression band and a silicone body integrally molded into said housingof said stimulator.
 19. A system comprising: a stimulator having anorifice within a housing thereof, said orifice having an opening incommunication with an outer surface of said housing; and a septumassembly coupled to said stimulator and configured to cover said openingof said orifice; wherein said septum assembly comprises first and secondhousing components each defined by at least an inner surface, a firstsealing strip disposed at least partially on said inner surface of saidfirst housing component, a second sealing strip disposed at leastpartially on said inner surface of said second housing component, and acompression member at least partially surrounding said housingcomponents; wherein said first and second sealing strips are configuredto create a seal over said opening of said orifice.
 20. The system ofclaim 19, wherein said compression member is configured to exert a forceon said first and second housing components such that said first andsecond sealing strips are in contact one with another to create a sealtherebetween.
 21. The system of claim 19, further comprising a leadextension assembly coupled to said stimulator, wherein said septumassembly is configured to be disposed within said lead extensionassembly.
 22. The system of claim 19, further comprising a headerassembly coupled to said stimulator, wherein said septum assembly isconfigured to be disposed within said header assembly.